Maybe a bit old news but the results to date are not really very exciting and certainly nothing minable has been intersected yet. So even discussion about potential mines and jobs is very very premature.

I couldn't agree more. Unless MINCO find something spectacular in the Melmerby Scar Limestone this project is a dead duck.

Dave Greenwood

Exploration to go into Northumberland:

http://www.thejournal.co.uk/news/north-east-news/pennines-drilled-zinc-mine-could-5743792 

Hence the PR effort.

Dave Greenwood

Whilst all this discussion about a mine and jobs is all premature both on the available core evidence, and the large amount of money required to initiate a project like this.
I feel I must take up Dave's point that they could use the old British Steell incline at Allenheads to site their operation,(if it ever comes to fruition).
I have stated before, and restate it now, the best place to access Nenthead/ West Allen ore-shoots, would be at the site of the incline which was driven, on Dunham's suggestion to investigate Killlhope- namely the Swinhope mine.
It is out of the way and would not hassle anyone. Indeed for years stood at the foot of the valley as monument to the search for non-ferrous minerals in the late 50's.

Good point John - but the controlling factor might be the planning aspects. As you say, Swinhope is isolated but that could count against any development on that site because it has now returned to a state of wild, if somewhat spoilt, natural beauty, typical of the North Pennines AONB as a whole, where the remains of previous mining are seen as an integral part of the landscape.

Another consideration would be the provision of services and in particular electrical power. As far as I can remember, extra power had to be laid on to Allenheads to support the BSC operations and that is presumably still in place. In contrast there is nothing comparable at Swinhope and a long row of new pylons across the fells would provoke a lot of opposition.

However it would seem from the PR that MINCO are at least thinking in terms of Allenheads. Time (and more boreholes) will tell.

Dave Greenwood

As I post this, the MINCO drilling rig is being dismantled ready to move.

Manxman

I am not sure how relevant Dave's point is on Grid access since Consolidateed Goldfields drove an incline to the base of the Great Limestone at Swinhope, a and then put in a mile of driveage under Killhope.
Presumably this was carried out using a Grid access. Although by the time I went down the drive there was no sign the Grid connection.
The othert major point in its favour is that in the Swinhope flats there is approximately 250,000 tons of high grade Lead and Zinc ore just waiting to be moved.
Not much I grant you but enough to stock pile and try out a mill if it ever comes to anything.

Does anyone know much much was left at Boltsburn mine? I hear there were large flats left untouched.

Does anyone know much much was left at Boltsburn mine? I hear there were large flats left untouched.

if memory serves it was drilled and found that the flats were still extensive several hundred metres beyond the point of abandonment

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If Boltsburn was reopened the fluorite specimen market would be awash!

As I understand it the main reason fo closing Boltsburn was the cost of hauling the ore to the shaft with the depressed lead prices at the time.
Although known for good clear fluorite, and the flats were kept dewatered for some time, after closing the mine for lead,in order to export this fluorite to Germany.
In my opinion this mine is unlikely to ever be re- opened, for the following reason:-
Weardale Lead, never reconsidered doing it after the war, when mining costs were a fraction of what they are now.
In any case this is a long way from Minco's known targets.

I explored the Flats and stopes in 1964 at Swinhope after Goldfields abandoned the mine. The High flats on No 1 vein were picked clean of ore, the Main vein was stoped out, Williams vein had a some zinc ore in the forehead. Foreheads of No 1 and No 2 veins were barren. Never did get to the end of the Goldfields Crosscut - candles would only burn at floor level at the 800 yard mark.

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John L. Dunham once told me that the Goldfields Cross Cut at Swinhope was where he and Tony Johnson "met their Waterloo!" but of course, like Allenheads, it was done without any surface drilling apart from the four holes used to establish the structure. Instead they relied on the old man's technique of driving an exploration level in the Tuft just under the Great Limestone.

Do you have a reference for the remark about the 250,000 tonnes of Lead and Zinc ore that are supposed to have been left in the Swinhope Flats? I can't find anything on that scale in Dunham 1990 but perhaps I've missed something.

Dave Greenwood

Sopwith Fan, I think the amount was quoted in the Future of Non Ferrous Mining in G.Britain, which was quite a lengthy tome. It also included lots of discussions in there on various mining options.
I think Peter must have seen other parts of the Flats as I can vividly remember the late Harry Parker mining a 6 inch vein of solid galena, and the walls of the flat being lined with sphalerite and galena.
Like Peter we could only go a few metres into the drive,due to bad air. Clearly Goldfields had needed a lot of ventilation for the drive, for large ducting was inside it.
Minco would just ignore this drive and either continue the incline down which is headed in the right direction or start spiralling it in order to gain the depth they need.

Thanks John - it's a long time since I read that particular tome but I'll look it up sometime. Dunham (1990) has a reference to it at the end of Chapter 15 but does not seem to have included the figure for the tonnage in his remarks about Swinhope.

Your incline plan makes a lot of sense but I still have reservations about the planning aspects. Let's hope the frackpot rent-a mob don't get involved.

Dave Greenwood

Having read through all the MINCO publicity I thought I would do a quick back-of-the-envelope calculation based on what they are saying. One Mtpa production would require a 20 Mt reserve given the usual 20 years life for a mine. At 4t/m3 that implies around 5,000,000 m3 of ore. Being generous and saying that the orebodies are 50 m wide and 10 m thick (way above anything currently known for the NPO) that would require a total strike length of 10 km. Is that realistic?

Dave Greenwood

Are we looking at Rake, Pipe, or Flats here ? , I would say its feasable in an open stope rake working, could be hard to get it from a pipe working, no experience in flat workings.

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10km strike and requiring an average grade of, say 10% Zn to be economic, (cf Lisheen and Navan in Ireland both with average head grades around 10% Zn (with 2% Pb and 10 g/t Ag), so the answer is almost certainly NO.

The Boltsburn Flats produced 513,609 tons averaging 17.3% Pb between 1901-31 so for a modern mine this would be about 6 months ore. Compare this to the estimate of 20Mt for the ENTIRE Northern Pennines (Dunham 1943) flourite and barite included - and this is the target Minco would need to find.

If Minco are trying to follow the Irish Zn-Pb model there is a fundamental issue in that the mineralizing event in the Irish Midlands was over by the time the limestone sequences in the Northern Pennines had even been deposited.

If Minco are trying to follow the Irish Zn-Pb model there is a fundamental issue in that the mineralizing event in the Irish Midlands was over by the time the limestone sequences in the Northern Pennines had even been deposited.

And that is the nub of the question. Is the NPO comparable with the CIO? To me it seems not because:

1. The Irish mineralisation seems to be concentrated on trend lines around the margin of the basement block whereas the mineralisation in the NPO is clearly controlled by the cupola areas of the Weardale Granite on the sub-Carbonifereous surface in the centre of the Alston Block - something that was shown by the work of Dunham and others from the 1930s onwards.

2. As you say the ages are different.

3. Also the stratigraphy and lithology are both different. No sign of reef limestones in the NPO and the replacement flats only occurred at very specific horizons - especially in the Great Limestone and are probably better compared with the West Cumberland hematites.

4. Different geothermal history.

You may well have other suggestions.

Dave Greenwood.

3. Also the stratigraphy and lithology are both different. No sign of reef limestones in the NPO and the replacement flats only occurred at very specific horizons - especially in the Great Limestone and are probably better compared with the West Cumberland hematites.

Agreed. The NPO and W Cumbria are clearly epigenetic deposits and may well reflect similar processes but with changing chemistry. You see the same in S Wales and I've suggested elsewhere that changing conditions from the Triassic (sabhka brines) into the lower Jurassic (subsiding marine basin 'oilfield brines') may have been responsible. You would need to look at strata of a similar age to the host-rocks to the Irish Midlands orebodies to seek anything resembling such deposits this side of the Irish Sea. Didn't the Craven Trough use to be regarded as worth a look? Seem to recall it coming up over beers at conferences in the past.

That mineralising activity in the L Carboniferous was not confined to the Irish Midlands is a reasonable assertion, though: for example Pb-Pb isotope data from Central Wales suggest that there was a major phase of Pb-Zn (minor Ag) extensional vein emplacement in the early Carboniferous. I'll have to dig out the work and see what mines worked this apparent L Carb event: Frongoch comes to mind but it's a while since I looked at the data so I need to check.

I've not read the various newspaper reports that have come out recently and, having seen what papers have made of information I've given them in the past, I wouldn't trust them to to get it right anyway, but at the meeeting in Nenthead, the only parallel Minco seemed to be suggesting between NP and the Irish situation was that mineralisation might be stronger at depth.

It seemed most of what they were saying about Ireland was to demonstrate to the locals that they were an experienced company with sucessful operations elsewhere and not some fly by night operation.

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